1. Field of the Invention
The invention relates in general to a sensing electrode structure, and more particularly, to a sensing electrode structure having a special design of a guard ring.
2. Description of the Related Art
Touch panels make a large scale industry. Various electronic products adopt touch panels as critical input/output devices for human-machine interfaces. The performance of touch panels depends on sensing electrodes and logic circuits connected thereto. Thus, the design and quality of the sensing electrodes dominates the performance of touch panels.
The sensing electrodes of a touch panel are generally formed on a transparent substrate. Light emitted from a display device penetrates the transparent substrate to reach a user. These sensing electrodes formed on the transparent substrate include multiple electrodes, which are connected to the logic circuits via multiple conducting wires.
With the compact trend of modern electronic products, the thickness of touch panels has become the critical factor of the thickness of touch screens. Further, multi-touch has become a fundamental function of human-machine interfaces. Thus, single layered and multi-point projected capacitive touch panels are currently one of the few touch panel forms that satisfy all of the above requirements.
With the constant increase resolution demand of display devices, the performance requirements of touch panels also become higher. To provide better performances, including the resolution, precision, sensing speed for fast-moving objects, for touch devices, more electrodes and conducting wires need to be fit into a limited touch area.
Distances between electrodes may be unequal due to routing limitations, thus incurring errors caused by non-linear factors when calculating coordinates of a touch point. Therefore, there is a need for a sensing electrode structure capable of mitigating effects of unequal distances between the electrodes, so as to provide consistent amounts of mutual capacitance between the electrodes to further reduce the non-linear factors in the coordinate calculations.